This invention relates to a bitumen composition. More particularly, this invention relates to a composition comprising bitumen and a low molecular weight olefin polymer.
Bitumen compositions, particularly asphalt compositions, comprising one or more polymeric modifiers are, of course, well known in the prior art. In general, the addition of a polymeric modifier to a bitumen composition, particularly an asphalt composition, will improve one or more of the bitumen properties such as penetrations, softening point, toughness, tenacity, heat resistance and the like such as taught in Japanese Pat. No. Sho 58[1983]-47057. Suitable polymeric additives include: block copolymers of an alkenyl aromatic monomer and a conjugated diolefin such as taught in U.S. Pat. No. 4,585,816 and the patents therein cited; olefin homopolymers and copolymers, particularly 1-butene homopolymers and copolymers, as taught in U.S. Pat. No. 3,915,914 and the patents therein cited; and isolefin homopolymers, particularly polyisobutylene, as taught in U.S. Pat. No. 3,615,803.
It is also known in the prior art to use asphalt compositions containing polymeric modifiers in the preparation of roofing materials and coatings such as is taught in U.S. Pat. No. 4,032,491 and the patents therein cited. While such roofing materials have exhibited improved properties, particularly improved penetration and heat resistant properties, these roofing materials have not demonstrated good low temperature properties, particularly low temperature flexibility, when used in extremely cold regions of the world. As a result, asphalt roofing materials, particularly asphalt shingles, are, generally, not used as roofing materials in extremely cold regions of the world or when used must be frequently replaced as the result of cracking and shrinking failures when subjected to extremely low temperatures for extended periods of time. Since asphalt roofing materials, particularly shingles, offer several advantages when such roofing materials can be used without frequent failure, the need for an improved asphalt roofing material which can be used in extremely cold regions of the world is believed readily apparent. In addition, it would be advantageous if such materials could be manufactured so as to facilitate handling when utilized in the regions which have cold temperatures.